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    <title>Document</title>
    <script>
      var num = 10;
      num++;
      console.log(num);
      //1.前置递增和后置递增如果单独使用 效果是一样的
      //2.后置递增 口诀：先返回原值 后自加1
      var age = 10;
      console.log(age++ + 10); //20
      console.log(age);
      var e = 10;
      var f = e++ + ++e;
      console.log(f); //22
    </script>
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